Structure of aluminum alloy driver’s cab on high speed EMU was introduced. The welding technique and welding difficulty of the driver’s cab and components was elaborated in detail. Aiming at eliminating porosity and irregular surface of welds in medium thick board,and distortion in the front wall. Its complex 3 D space structure caused locality wave distortion on the three-dimensional curved roof and outer contour size of the aluminum alloy driver’s cab was unqualified,bad welding quality of over-head position welding in driver’s cab,further studied the welding process of the cab,analyzed the causes of welding problems,and formulated reasonable process measures,effectively ensuring the welding quality of the cab to meet the design and operation requirements.